This Core is responsible for all epidemiological, statistical, and data management aspects of the Program Project. The Section of Clinical Epidemiology, including the Rochester Epidemiology Project, provides the nucleus for the population-based follow-up aspects of Project I by assuring complete ascertainment of all clinical material pertaining to the residents of Olmsted County. The Section of Biostatistics provides statistical expertise including state-of-the-art analysis and data handling resources for all of the projects but especially for Projects I, II, and IV since Project III involves primarily basic science. The Survey Research Center (within the Section of Biostatistics) provides expertise in the follow-up of Mayo patients and has there sources and experience to assure the completeness of the follow-up required in Project I. The existence of this Core assures a uniform plan of protocol design, data handling, and statistical analysis and further assures that appropriate resources are available to all investigators at any time.